Australia is one of the most sparsely inhabited countries on earth. Twenty-four million people—about the population of Texas—are spread out over an area roughly the size of the continental United States. The country's "last frontier" is the Cape York Peninsula in northern Queensland, home to thousands of square miles of unspoiled rainforest and savannah. But it might take you days to get to "the tip," the northernmost point of the second southernmost continent.

Wanted: tourists with four-wheel drive and two weeks free.From the popular tourist sights at Cairns, it's a 600-mile drive, mostly over bumpy dirt roads, to get to the tip of the continent. This can be a two-week camping trip, round-trip. Don't even think about trying it during the rainy season. But arriving at Pajinka, as the Aborigines call it, is worth the wait. At low tide, there are miles of sandy shore and turquoise water at Cape York. The resort here closed in 2002, so if you get here before the tour buses, you might have the beach all to yourself. Be warned before you swim: the Torres Strait is known for its treacherous currents and saltwater crocodiles.

Time for some strait talk.About fifteen minutes' walk from the parking lot, you can clamber down some rocks and take your photo with the famous sign that reads "You are standing at the northernmost point of the Australian continent." Captain Cook discovered Cape York in 1770, naming it after the Duke of York. Today, a circular brass plaque marks off the distances to cities across the continent and even across the Pacific. Seventy miles to the north, past the Torres Strait Islands, is New Guinea.

During the Ice Age, you could walk to New Guinea.The island chain connecting Australia and New Guinea is actually a series of submerged mountain peaks, part of the Great Dividing Range that forms the backbone of the Cape York Peninsula. Thousands of years ago, when sea levels were lower, Australia and New Guinea were part of a massive continent called Sahul, and there was a land bridge here between the two countries as recently as 12,000 years ago. This explains why New Guinea has kangaroos, and also how the first people arrived in Australia. Coincidentally, the Cape York Peninsula is also where Europeans first met Aboriginal Australians in 1606. The resulting battle was a sad sign of things to come.

Australia is movin' on up.Cape York is getting closer to Asia every year. The Australian plate is the fastest moving tectonic plate on the planet, which means the continent drifts northward about 2 inches every year. Over time, this shift has had an effect on Australia's maps and GPS devices, which are now 5 feet out of whack nationwide. To correct the error, Australia's coordinate system will move the entire nation 5.9 feet north on New Year's Day, its first update since 1994. I hope they do it at night, so nobody feels a thing.

Explore the world's oddities every week with Ken Jennings, and check out his book Maphead for more geography trivia.